1. Field of the Invention
This invention relates to a method for minimizing defect sources that are located inside a high density plasma reactor. Particularly, the present invention relates to a method for cleaning the high density plasma reactor by a cycle purge process in which defect sources are clean up by gas.
2. Description of the Prior Art
Currently, the high density plasma reactor has become an important piece of equipment for high density plasma provides an efficient way to overcome many disadvantages of both conventional chemical vapor deposition (CVD) and conventional physical vapor deposition (PVD) process. Further, owing to the fact that the reaction of high density plasma process comprises both depositing reaction and etching reaction at the same time, it is natural that high density plasma also provides an efficient way of performing the etching process.
However, because the density of high density plasma is larger than both conventional CVD and conventional PVD, the quantity of defect sources inside the high density plasma reactor is larger than that of a conventional reactor. Significantly, because the etching process will remove something from the wafer, the quantity of defect sources is further increased. Thus, when a high density plasma reactor is used to continuously process numerous wafers or to continuouly perform numerous processes, the risk that the reactor is contaminated by defect sources cannot be neglected.
A practical example is the high density plasma etcher that is used to perform a W (tungsten) etching back process. Whenever numerous wafers are processed in regular order, it is unavoidable that defect sources continuouly accumulated and some defect sources will drop on top of the surface of the wafer. In other words, some invidual external defects are formed on the wafer, and according to practical experience, these external defects are inclined to collect at the center of the wafer.
Therefore, in order to enhance the practicality of high density plasma, it is desired for a method of cleaning the high density plasma reactor is to eliminate (or at least minimize) the risk of defects. Furthermore, in order not to degrade performance of the high density plasma, the required method should not be accomplished by changing the parameters of high density plasma such as density, temperature and so on.